You have the ability to copy extremely weakened versions of the powers of Parahumans and three slots to use those powers with. To copy a Parahuman's power you must get within a meter of them. If you copy the power of an Endbringer or Entity, you get every single power they have separately, instead of just one power.
You can switch what power is in your slots at will. Every day you get a charge (two with Negentropy) you can use to increase the strength of a power, though you can save these charges as well. Once a power reaches the same strength as the original, you can no longer dump charges into it.
On average it takes 7 charges to fully charge a weak power, 14 charges to fully upgrade a mid-level power, 21 charges to fully upgrade a high-level power, and 28 charges to fully upgrade an extremely powerful power.
You can also use those charges to increase how many slots you have, to a maximum of five. It takes 30 charges to fully increase the number of slots you have, though before you fully gain a new slot you can place an even weaker version of a power in that slot. For example, if you have a slot that has 15 charges put into it, the power is half as powerful as it would be if it were in a full slot. You can increase the number of daily charges by investing 60 and 90 charges, up to a maximum of 3 (or 5 with Negentropy).
Your powers, even when strengthened to their max, will never be the same as the original Parahuman's power. Instead, they will be a side-grade, a power that could have come from the Parahuman's Shard, but didn't. You can spend 3 charges to reroll the power expression.